A battery remote monitoring and performance evaluation system

Abstract

The invention discloses a battery remote monitoring and performance evaluation system, comprising a data acquisition module, a battery unit, a remote discharge module, a terminal controller, a database server and a control center. The control center and the database server exchange data through a network. The specific steps are as follows: discretely collect battery discharge parameters, based on the collected data, use an interpolation method to calculate the relevant discharge ratio (%), discharge capacity (AH), corresponding voltage v, corresponding temperature, and discharge current values ​​and list them, predict the battery remaining capacity and actual capacity, and upload the collected data to a central management platform software through the network in real time for analysis and storage, so as to monitor the real-time operating environment of the substation DC equipment operating parameters. At the same time, the system will calculate the battery remaining life and actual capacity evaluation based on the real-time monitoring data, providing a scientific and reasonable basis for the battery replacement plan.

Description

Technical Field

[0001] The present invention relates to a battery status evaluation technology, and more specifically, to a battery remote monitoring and performance evaluation system. Background Art

[0002] The so-called intelligent power monitoring system refers to a hardware and software device that uses computer technology, metering protection devices and bus technology to centrally detect and manage the real-time data, switch status and remote control of the power transmission and transformation system. At present, the intelligent power monitoring system has the characteristics of unit modularization, transmission networking and monitoring graphics.

[0003] Although the intelligent power monitoring system has made great progress, it still has limitations: the monitoring applications of various electrical parameters and switch status parameters are far more than the monitoring applications of environmental parameters. Practical experience shows that in addition to the reasons of the electrical equipment itself, equipment failure caused by the backup power supply is also an important factor causing the transmission and transformation network to be unable to operate stably. Therefore, monitoring of the backup power supply is also very necessary. In domestic and foreign industry applications, there are relatively mature research and application examples of online monitoring of batteries, but the solution given is to install insulation detection systems, battery inspection systems, voltage monitoring systems, environmental monitoring systems, transformer monitoring systems, etc. These systems have the following problems:

[0004] 1. Each system operates independently, forming a monitoring "island" phenomenon, which makes it impossible to effectively manage and achieve the effect of security management.

[0005] 2. The coexistence of multiple systems not only increases the investment cost, but also greatly increases the subsequent maintenance cost. In addition, the simultaneous operation of equipment from multiple manufacturers will also cause disputes and waste the power supply company's time and energy.

[0006] 3. The device has a single function.

[0007] 4. Generally, only a small amount of important information is uploaded to the monitoring center by the networked monitoring device, and detailed information such as the operating status of the DC equipment and environmental parameters cannot be reflected in real time.

[0008] 5. The monitoring data is discrete, and the status judgment mainly relies on manual inspection to discover problems, which affects the safe operation of the power grid.

[0009] 6. The operation and maintenance of the backup power supply batteries are not taken seriously, and the battery pack cannot be guaranteed to operate in good condition, which affects the safe operation of the power grid. Various accidents caused by battery failures also occur frequently in the power industry, some of which even cause fires and power outages in the entire station, posing a great safety hazard to the reliable operation of the power system.

[0010] 7. As for the battery online monitoring system, some online monitoring devices for batteries have been developed. The devices can provide effective technical means for the daily maintenance and monitoring of batteries, and realize comprehensive analysis, intelligent management, automatic alarm, network monitoring and other functions. However, the device has a single function and can only provide monitoring functions. On the other hand, it cannot evaluate the remaining life of the battery, the actual capacity, and remotely maintain the battery. At present, the measurement technology of battery pack charging and discharging current, voltage, temperature, etc. is basically mature. The main research direction is the measurement of monomer internal resistance. Research on insulation impedance monitoring, battery online balancing and battery remaining life evaluation has not yet started in China.

[0011] 8. As for the insulation monitoring devices of DC systems, the devices currently used have a single function and can only provide monitoring functions and send out warning signals when conditions are met. They cannot monitor insulation degradation, achieve isolation protection, and accurately monitor the grounding position.

[0012] 9. The battery pack does not have the ability to balance voltage. The voltage changes of some batteries in the battery often cause other batteries to be overcharged or undercharged, resulting in battery capacity reduction, shortened battery life, electrolyte drying up, etc., affecting the reliability of the entire system operation. Summary of the invention

[0013] In view of the above problems, the present invention provides a system capable of effectively monitoring and evaluating the status of a battery.

[0014] In order to achieve the above object, the present invention provides a battery remote monitoring and performance evaluation system, wherein a data acquisition module is independently set for each battery group to be evaluated; each battery group is provided with a backup battery unit, and the battery group and the corresponding backup battery unit are connected to a remote discharge module; the data acquisition module and the corresponding remote discharge module are connected to a terminal controller; the terminal controller is connected to a database server and a control center through a communication network, and the control center and the database server exchange data through the network;

[0015] Wherein, the control center evaluates the battery pack according to indicators including the service life and remaining capacity of the battery pack;

[0016] The database server is used to store the collected data information and provide database services for the control center;

[0017] The terminal controller transmits the battery group data of each site collected in real time to the database server through network transmission;

[0018] The data acquisition module remotely monitors and collects the battery group terminal voltage, battery cell voltage, battery cell temperature, current, battery internal resistance, ambient temperature, battery operation status (status includes: normal working status includes: balanced charging status, floating charging status, discharge / power supply status; abnormal status: abnormal working parameters occur in any of the balanced charging status, floating charging status and discharge / power supply status, such as excessively high or low cell voltage, voltage difference between batteries), bus voltage parameters in real time;

[0019] The bus voltage parameters specifically include the parameters required for DTU battery capacity and life prediction;

[0020] The remote discharge module remotely controls the corresponding battery packs to achieve constant current discharge group by group; after the discharge is completed, the battery packs are charged and restored online through the power supply system;

[0021] S1: Based on the above system, a battery capacity prediction function is provided, including the following steps:

[0022] S1-1: discretely collected battery discharge parameters, including discharge ratio (%), discharge capacity (AH), corresponding voltage v, corresponding temperature, and discharge current;

[0023] S1-2: Based on the collected data, with an interval of 5% of the actual capacitance, the interpolation method is used to calculate the relevant discharge ratio (%), discharge capacity (AH), corresponding voltage v, corresponding temperature, and discharge current values, and a discharge variable table is drawn;

[0024] S1-3: Predict the battery discharge capacity according to the following formula (1):

[0025]

[0026] Where C(t) represents the predicted battery discharge capacity, V t Indicates the lowest current voltage of the battery cell in the battery pack operating parameters, V i Indicates the current voltage V in the discharge variable table t The starting voltage of the interval, V i+1 Indicates the current voltage V in the discharge variable table t The end voltage of the interval, I t Indicates the current discharge current value of the battery pack, and I0 indicates V t The discharge current value at the starting point of the interval, C(i) represents the starting discharge capacity of the interval where the current voltage Vt is located in the discharge variable table, and C(i+1) represents the current voltage Vt in the discharge variable table. t The final discharge capacity of the interval, T t Indicates the current ambient temperature during discharge, T0 indicates V tThe ambient temperature at the starting point of the interval, when V t When there are multiple intervals, the first interval from the left in the table shall prevail. When Vt exceeds the voltage value corresponding to the discharge ratio of 0%, C(t) takes the value of 0;

[0027] S1-4: Predicting the remaining battery capacity and actual capacity

[0028] Remaining battery capacity C(left) = C(total) - C(t) Formula (2)

[0029] The actual battery capacity C = C(left) + C(actual) Formula (3)

[0030] In the formula, C(total) represents the actual capacity of the battery recorded when establishing the discharge variable table, C(left) represents the remaining capacity of the battery calculated according to the current state, C(actual) represents the actual discharge capacity of the battery collected by the controller, and C represents the actual capacity of the battery in the current state. In step S1-4, when Vt is lower than the voltage value corresponding to the change in the battery capacity column from the left side of the table, C(t) is calculated according to the discharge amount reported by the controller, that is, C(t) = C(actual);

[0031] S2: Based on the above system, a battery remaining life prediction function is provided, including the following steps:

[0032] When the battery discharges no less than 30% of the rated capacity of the battery, after the battery discharge is completed, the life is calculated based on the working parameters when the last discrete collection of the discharge state is completed. The working parameters include: discharge ratio (%), discharge capacity (AH), corresponding voltage v, corresponding temperature, and discharge current value:

[0033]

[0034] or

[0035] Y(t)=10-Y(i) formula (5)

[0036] Where, Y(t) represents the calculated remaining life of the battery, which is the smaller value between the result of formula (4) and the result of formula (5), and Y(i) represents the known working time of the battery pack;

[0037]

[0038] Where k represents the aging coefficient, y = known working years - 1;

[0039] In a preferred embodiment, when the data acquisition module detects that the internal resistance of a single battery pack exceeds a set threshold value, the control center automatically issues an alarm through the terminal controller;

[0040] There are two methods to measure internal resistance, namely AC method or DC method;

[0041] The AC method is to generate an AC voltage of a fixed frequency through an AC signal generator, measure the current when this signal passes through the battery, and calculate the ratio of voltage to current to get the resistance value; the DC method is to discharge the battery under different current conditions, measure the voltage value during discharge, and calculate the resistance value by calculating the ratio of voltage difference to current difference.

[0042] In the preferred method, the actual capacity of the battery needs to be predicted based on the comprehensive evaluation combined with the battery internal resistance comparison standard to obtain the accurate actual capacity of the battery: the specific comparison standard is processed as follows:

[0043] In actual engineering applications, the actual internal resistance of the battery is compared with the internal resistance of new batteries in the same batch, using method 1; or the average internal resistance of the same group of batteries, using method 2; or compared with the value of the last internal resistance test, using method 3;

[0044] Method 1: The production factors of the same batch of batteries are basically the same, so the internal resistance is basically close; when the internal resistance of a specific battery is higher than that of a new battery, it means that the capacity has decreased and actual testing is required;

[0045] Method 2: The internal resistance of the same group of batteries should be basically the same because the use environment is exactly the same; when the internal resistance of a specific battery is higher than the average internal resistance of the same group, it means that the capacity has decreased; if the internal resistance is 30% higher than the average internal resistance, it should be paid close attention to, and if it is higher than 100%, it is considered that it needs to be replaced;

[0046] Method 3: Compare the relationship between the internal resistance of the battery and the decrease in the actual remaining capacity of the battery. When the actual remaining capacity of the battery is between 100% and 70% of the nominal value, the corresponding relationship between the capacity decrease and the internal resistance increase does not change significantly. When the actual remaining capacity of the battery is less than 25% of the nominal value, the internal resistance increase trend gradually accelerates.

[0047] The discharge variable table records the actual measured values ​​of the corresponding discharge capacity, voltage, temperature and discharge current starting from 0% discharge ratio and at intervals of 5% until 100%.

[0048] Beneficial purpose of the present invention: The present invention adopts Internet of Things technology and intelligent sensor technology to remotely monitor and collect parameters such as battery group terminal voltage, battery cell voltage, battery cell temperature, current, ambient temperature, battery operating status, bus voltage, etc. in real time. The collected data is uploaded to the central management platform software through the network for analysis and storage in real time, so as to monitor the real-time operating environment of the substation DC equipment operating parameters. At the same time, the system will calculate the remaining battery life and actual capacity evaluation based on the real-time monitoring data, providing a scientific and reasonable basis for the battery replacement plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the principle structure of the system of the present invention;

[0050] Figure 2 is a pre-stored discharge variable table;

[0051] Figure 3 is the updated full discharge variable table. DETAILED DESCRIPTION

[0052] like Figure 1 As shown, the battery remote monitoring and performance evaluation system of the present invention first independently sets a data acquisition module for each battery group to be evaluated; each battery group is provided with a backup battery unit, and the battery group and the corresponding backup battery unit are connected to a remote discharge module; the data acquisition module and the corresponding remote discharge module are connected to a terminal controller; the terminal controller is connected to a database server and a control center through a communication network, and the control center and the database server exchange data through the network. Among them,

[0053] 1. Control center. It includes online monitoring system, DC system insulation impedance monitoring system and battery remote verification discharge maintenance system. The system will provide effective technical means for the daily maintenance monitoring and maintenance of DC equipment, and realize remote maintenance, comprehensive analysis, intelligent management, automatic alarm and network monitoring and other advanced functions. At the same time, it studies various operation and maintenance parameters of batteries from multiple angles and has a battery evaluation system, which is used to evaluate, distinguish and screen batteries according to the main indicators such as battery life and remaining capacity.

[0054] 2. Database server: It is used to store the collected data information and provide database services for the control center.

[0055] 3. Terminal controller. The battery group data of each site collected by the system in real time is transmitted to the database server through various network transmission methods. Through the control center, the comprehensive analysis and processing of the uploaded power environment data of each site is completed, and the operating parameters and operating status of the DC equipment at each site are automatically displayed and analyzed, realizing remote maintenance, comprehensive analysis, intelligent management, automatic alarm, network monitoring and other functions.

[0056] 4.Data acquisition module.

[0057] (1) Real-time monitoring function: Real-time remote monitoring and collection of battery group terminal voltage, battery cell voltage, battery cell temperature, current, ambient temperature, battery operating status, bus voltage and other parameters.

[0058] (2) Battery internal resistance monitoring function: Based on the conventional online monitoring of the battery pack, the advanced online internal resistance testing technology is adopted to test the internal resistance of each battery online, so as to timely and accurately understand the performance status of the battery and find the faulty single cell. Real-time alarm function: When the internal resistance value of a single cell is detected to exceed the set threshold value, the system will automatically alarm. The normal operation of the system is not affected during the test. This module is composed of various sensors, which are used to collect the battery pack terminal voltage, battery cell voltage, battery cell temperature, current, ambient temperature, battery operating status, bus voltage and battery internal resistance. Except for the internal resistance test, all others are monitored in real time by sensors, so it is called conventional measurement. The test of internal resistance cannot be obtained directly through sensors. There are two methods in the module to achieve the measurement of internal resistance, namely AC method and DC method. The AC method is to use an AC signal generator to generate an AC voltage with a fixed frequency (different AC signal generators have different frequencies), measure the current when this signal passes through the battery, and calculate the ratio of voltage to current to get the resistance value; the DC method is to discharge the battery under different current conditions (different industry standards have specific provisions for discharge current), measure the voltage value during discharge, and calculate the ratio of voltage difference to current difference to get the resistance value. The AC method is simple to measure, and can be measured at any time by controlling the AC signal generator, and can be monitored in real time; the DC method requires the battery to be controlled to discharge before measurement, so it does not have real-time performance.

[0059] 5. Remote discharge module. Remotely control the battery packs to achieve "online" constant current discharge one by one. During the discharge process, the tested battery pack does not need to be disconnected from the system and remains online in real time to maximize the remaining capacity of the system's backup battery pack to achieve the purpose of safe discharge capacity testing. After the discharge is completed, the system can perform online charging and recovery of the battery pack. The entire verification discharge process is completed automatically. During the discharge process, there is no need for staff to go to the site for operation or staff on duty. The system background automatically records the relevant results, which greatly saves labor costs and improves labor efficiency.

[0060] The battery remaining life prediction function calculates the battery capacity attenuation ratio based on the battery discharge capacity to obtain the current battery aging coefficient. A large number of battery tests have found that the battery aging model is similar to the battery discharge curve. The aging coefficient of a new battery is 1, and its aging coefficient is 0 at the end of its life.

[0061] The present invention is based on the self-learning discharge curve method and the small current internal resistance test method, and adopts curve fitting and piecewise linear interpolation method to comprehensively evaluate the actual capacity of the battery. The comprehensive formula of the fitting curve and the piecewise difference is:

[0062]

[0063] In the formula: C(t) represents the battery's discharged capacity predicted based on the measured working parameters of the battery pack after the battery starts to discharge, Vt represents the lowest current voltage of the battery cell in the measured working parameters of the battery pack after the battery is discharged, Vi represents the starting voltage of the interval where the current voltage Vt is located in the discharge variable table, Vi+1 represents the ending voltage of the interval where the current voltage Vt is located in the discharge variable table, It represents the current discharge current value of the battery pack, I0 represents the discharge current value at the starting point of the interval where Vt is located in the discharge variable table, C(i) represents the starting discharge capacity of the interval where the current voltage Vt is located in the discharge variable table, C(j) represents the ending discharge capacity of the interval where the current voltage Vt is located in the discharge variable table, Tt represents the ambient temperature during the current discharge, and T0 represents the ambient temperature at the starting point of the interval where Vt is located in the discharge variable table. According to the prediction of the actual capacity of the battery, a comprehensive evaluation should be conducted in combination with the battery internal resistance comparison standard to obtain the accurate actual capacity of the battery. Among them, the battery internal resistance comparison standard adopts the following method: in actual engineering applications, the actual internal resistance of the battery is compared with the internal resistance of the new battery of the same batch (Note 1), or the average internal resistance of the same group of batteries (Note 2), or compared with the value of the last internal resistance test (Note 3). Note 1: The production factors of the batteries of the same batch are basically the same, so the internal resistance is basically close. When the internal resistance of a specific battery is higher than that of a new battery, it means that the capacity has decreased. However, the capacity decrease and the internal resistance increase are not a functional correspondence, and actual testing is required. Note 2: The internal resistance of the same group of batteries is basically the same because the use environment is exactly the same. When the internal resistance of a specific battery is higher than the average internal resistance of the same group, it means that the capacity has decreased. Generally, if the internal resistance is 30% higher than the average internal resistance, it should be paid close attention, and if it is higher than 100%, it is considered to need to be replaced. However, only comparing the deviation of the specific internal resistance of a battery from the average value cannot directly reflect the capacity decrease. Note 3: It is generally believed that when the actual remaining capacity of the battery is around 100%-70% of the nominal value, the corresponding relationship between the capacity decrease and the internal resistance increase does not change significantly. When the actual remaining capacity of the battery is less than 25% of the nominal value, the internal resistance increases gradually.

[0064] Based on the above principles, the specific prediction content is explained below:

[0065] 1. Definition of battery capacity and life

[0066] (I) Capacity

[0067] Battery capacity: The amount of electricity that can be obtained from a battery under certain discharge conditions is called the battery capacity, represented by the symbol C. The commonly used unit is ampere-hour, referred to as ampere-hour (A·H). The capacity of a battery can be divided into rated capacity, actual capacity, and residual capacity.

[0068] 1. Rated capacity

[0069] Rated capacity: refers to the ampere-hour of electricity that a fully charged battery can provide under specified conditions, as indicated by the manufacturer. Generally, the amount of electricity that a fully charged battery can output when it is continuously discharged to 1.75V at a 20-hour rate (equivalent to 1 / 20 of the rated capacity) at an average electrolyte temperature of 25°C. This is generally the nominal capacity of the battery.

[0070] 2. Actual capacity

[0071] Actual capacity: refers to the maximum amount of electricity that a battery can actually output under certain conditions after it is fully charged.

[0072] 3. Remaining capacity

[0073] Remaining capacity: refers to the difference between the actual capacity of the battery and the amount of electricity discharged.

[0074] (ii) Lifespan

[0075] 1. Design life of battery

[0076] The design life of a battery generally refers to its service life, which is the calendar time from when a new battery is used or shelved until the actual capacity of the battery drops to 80% of the rated capacity, usually 10 years.

[0077] 2. Remaining battery life

[0078] The remaining life of a battery is generally the difference between the design life of the battery pack and the working time of the battery pack.

[0079] 2. Battery capacity calculation method

[0080] 1. Calculation conditions

[0081] In the discharge state, the current working voltage (Vt), ambient temperature (Tt), and discharge current (It) are used as the calculation basis, and the remaining capacity (Ct) of the old battery is calculated according to the interpolation method. Each time the new battery working parameters are uploaded, the battery discharge capacity (Ct) must be calculated, and the battery remaining capacity (Cleft) is calculated based on this.

[0082] The battery discharge capacity (Ct) calculated from the battery with the lowest operating voltage (Vt) in the same battery pack should be used as the basis for calculating the remaining capacity (Cleft) of the battery pack.

[0083] 2. Calculation method

[0084] According to the current battery working voltage, the interpolation method is used to calculate based on the pre-recorded battery discharge curve. The specific method is to record 21 reference points in advance according to the battery discharge curve at an interval of 5% of the actual capacitance, see Figure 2 .

[0085] (1) First, the battery discharge capacity is predicted based on the battery operating parameters. The calculation formula is as follows:

[0086]

[0087] In formula (1), the parameters are explained as follows: C(t) represents the battery discharge capacity predicted based on the measured battery pack operating parameters after the battery starts to discharge. V t Indicates the lowest current voltage V of the battery cell among the battery pack operating parameters measured after the battery is discharged. i Indicates the starting voltage of the interval where the current voltage Vt is located in the discharge variable table. V i+1 Indicates the end voltage of the interval where the current voltage Vt is located in the discharge variable table. t Indicates the current discharge current value of the battery pack. I0 indicates the discharge current value at the starting point of the interval where Vt is located in the discharge variable table. C(i) indicates the starting discharge capacity of the interval where the current voltage Vt is located in the discharge variable table. C(i+1) indicates the ending discharge capacity of the interval where the current voltage Vt is located in the discharge variable table. T t Indicates the ambient temperature during the current discharge. T0 indicates the ambient temperature at the starting point of the interval where Vt is located in the discharge variable table. When Vt corresponds to multiple intervals, the first interval from the left in the table shall prevail. When Vt exceeds the voltage value corresponding to the discharge ratio of 0%, C(t) takes the value of 0.

[0088] Calculation example 1: At a certain moment, the battery operating voltage Vt is measured to be 2.005V, the discharge current It is 39.9A, and the ambient temperature Tt is 32.3℃. Then, according to formula (1), we can get

[0089]

[0090] Calculation example 2: At a certain moment, the operating voltage Vt of the battery is measured to be 2.182V, the discharge current It is 39.9A, and the ambient temperature Tt is 32.3°C. Since Vt is greater than 2.126V, C(t)=0.

[0091] (2) Predicting the remaining battery capacity and actual capacity

[0092] Remaining battery capacity C(left) = C(total) - C(t)

[0093] The actual battery capacity C = C (left) + C (actual)

[0094] C (total): the actual capacity of the battery recorded when the meter was created, i.e. Figure 2 The rightmost value of the discharge capacity column in the discharge variable table. C(t): The discharge capacity of the battery calculated using formula (1) based on the current state. C(left): The remaining capacity of the battery calculated based on the current state, which is the difference between C(total) and C(t). C(actual): The actual discharge capacity of the battery collected by the controller. C: The actual capacity of the battery in the current state calculated, which is the sum of C(left) and C(actual).

[0095] Calculation example 3: At a certain moment, the working voltage Vt of the battery is measured to be 2.005V, the discharge current It is 39.9A, the ambient temperature Tt is 32.3℃, and the discharged capacity is 100AH. Then, according to formula (1), C(t) = 128.1AH. When C(total) is 400AH, C(actual) is 100AH. Calculation yields:

[0096] Battery remaining capacity C(left) = 400-128.1 = 271.9AH

[0097] Actual capacity C = 271.9 + 100 = 371.9AH

[0098] (3) If the pre-stored discharge variable table is Figure 3 format, when Vt is lower than the voltage value corresponding to the change in the battery capacity column from the left side of the table, C(t) is calculated according to the discharge amount reported by the controller, that is, C(t) = C(actual).

[0099] 3. Calculation method of remaining battery life

[0100] When the battery discharges no less than 30% of the rated capacity of the battery, after the battery discharge is completed, the remaining life of the battery is calculated based on the working parameters collected last time when the discharge state is reached.

[0101]

[0102] Y(t): The calculated remaining life of the battery, which is the smaller value between the result of formula (4) and the result of formula (5). Y(i): The known working time of the battery pack

[0103] k: aging coefficient,

[0104] Where y = known years of work experience - 1.

[0105] Calculation example 4: At a certain moment, it is measured that the working voltage Vt of a battery that has been in operation for 5 years is 1.989V when it stops discharging, the discharge current It is 39.9A, the ambient temperature Tt is 32.3°C, and the discharged capacity is 160AH. Then, according to formula (1), C(t) = 192.8AH. When C(total) is 400AH and C(actual) is 160AH, the actual capacity of the battery is C = 400-192.8+160 = 367.2AH.

[0106] According to formula (4), we get

[0107] According to formula (5), Y(t)=10-5=5 years, and the final value of Y(t) is 5 years.

[0108] 4. Discharge variable table

[0109] 1. Discharge variable table update standard

[0110] (1) When there is no discharge record for the battery pack, the discharge variable table is the system default discharge variable table.

[0111] (2) When the battery discharge capacity exceeds 95% of the battery capacity, the corresponding data in the discharge variable table is updated after the discharge is completed.

[0112] (3) Discharge variable table update method

[0113] When the battery discharge capacity is not less than 95% (complete discharge), the voltage, current, and temperature data corresponding to the discharge percentage position in the discharge variable table are updated with the measured data, and the discharge capacity data are updated according to the calculation, where the 100% discharge data is based on the last collected data (the 5% interval discharge power value is accurate to the unit digit when the battery capacity is ≥100AH, accurate to 1 decimal place when the battery capacity is 50AH≤<100AH, and accurate to 2 decimal places when the battery capacity is <50AH, and the rest are rounded). Update example: A battery with a rated capacity of 400AH discharges 369AH for the first time and stops discharging because the voltage reaches the discharge cut-off voltage of 1.8V. The last collected working voltage Vt before stopping discharge is 1.801V.

[0114] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A battery remote monitoring and performance evaluation system, characterized in that: A data acquisition module is independently provided for each battery group to be evaluated, and a backup battery unit is provided for each battery group. The battery group and the corresponding backup battery unit are connected to a remote discharge module; the data acquisition module and the corresponding remote discharge module are connected to a terminal controller; the terminal controller is connected to a database server and a control center through a communication network, and the control center and the database server exchange data through the network; The control center evaluates the battery pack according to the indicators of the battery pack's service life and remaining capacity; The database server is used to store the collected data information and provide database services for the control center; The terminal controller transmits the battery group data of each site collected in real time to the database server through network transmission; The data acquisition module remotely monitors and collects the battery group terminal voltage, battery cell voltage, battery cell temperature, current, battery internal resistance, ambient temperature, battery operating status, and bus voltage parameters in real time; The bus voltage parameters specifically include the DTU battery capacity and parameters required for life prediction; The remote discharge module remotely controls the corresponding battery packs to achieve constant current discharge group by group, and after the discharge is completed, the battery packs are charged and restored online through the power supply system; The operation steps based on the above system are: S1: Provides battery capacity prediction function, including the following steps: S1-1: discretely collected battery discharge parameters, including discharge ratio, discharge capacity, corresponding voltage v, corresponding temperature, and discharge current; S1-2: Based on the collected data, with 5% of the actual capacitance as the interval, the interpolation method is used to calculate the values ​​of the relevant discharge ratio, discharge capacity, corresponding voltage, corresponding temperature, and discharge current, and a discharge variable table is drawn; S1-3: Predict the battery discharge capacity according to the following formula (1): Where C(t) represents the predicted battery discharge capacity, V t Indicates the lowest current voltage of the battery cell in the battery pack operating parameters, V i Indicates the current voltage V in the discharge variable table t The starting voltage of the interval, V i+1 Indicates the current voltage V in the discharge variable table t The end voltage of the interval, I t Indicates the current discharge current value of the battery pack, and I0 indicates V t The discharge current value at the starting point of the interval, C(i) represents the starting discharge capacity of the interval where the current voltage Vt is located in the discharge variable table, and C(i+1) represents the current voltage Vt in the discharge variable table. t The final discharge capacity of the interval, T t Indicates the current ambient temperature during discharge, T0 indicates V t The ambient temperature at the starting point of the interval, when V t When there are multiple intervals, the first interval from the left in the table shall prevail. When Vt exceeds the voltage value corresponding to the discharge ratio of 0%, C(t) takes the value of 0; S1-4: Predicting the remaining battery capacity and actual capacity Battery remaining capacity C(left) = C(total) - C(t) Formula (2) The actual capacity of the battery C = C(left) + C(actual) Formula (3) In the formula, C(total) represents the actual capacity of the battery recorded when the discharge variable table is established, C(left) represents the remaining capacity of the battery calculated according to the current state, C(actual) represents the actual discharge capacity of the battery collected by the controller, and C represents the actual capacity of the battery in the current state. In step S1-4, when Vt is lower than the voltage value corresponding to the change in the battery capacity column from the left side of the table, C(t) is calculated according to the discharge amount reported by the controller, that is, C(t) = C(actual); S2: Predicting the remaining battery life, including the following steps: When the battery discharges no less than 30% of the rated capacity of the battery, after the battery discharge is completed, the life is calculated based on the working parameters when the last discrete acquisition is made to the discharge state: or Y(t)=10-Y(i) Formula (5) Where, Y(t) represents the calculated remaining life of the battery, which is the smaller value between the result of formula (4) and the result of formula (5), and Y(i) represents the known working time of the battery pack; Where k represents the aging coefficient, and y = known working years - 1.

2. The battery remote monitoring and performance evaluation system according to claim 1, characterized in that: When the data acquisition module detects that the internal resistance of a single battery pack exceeds a set threshold value, the control center automatically issues an alarm through the terminal controller.

3. The battery remote monitoring and performance evaluation system according to claim 2, characterized in that: There are two methods to measure internal resistance, namely AC method and DC method. The AC method is to generate an AC voltage of a fixed frequency through an AC signal generator, measure the current when this signal passes through the battery, and calculate the ratio of voltage to current to get the resistance value; the DC method is to discharge the battery under different current conditions, measure the voltage value during discharge, and calculate the resistance value by calculating the ratio of voltage difference to current difference.

4. The battery remote monitoring and performance evaluation system according to claim 1, characterized in that: Based on the prediction of the actual capacity of the battery, a comprehensive evaluation needs to be conducted in combination with the battery internal resistance comparison standard to obtain the accurate actual capacity of the battery. After the specific comparison standard, the following processing is adopted: Method 1: The production factors of the same batch of batteries are basically the same, so the internal resistance is basically close; when the internal resistance of a specific battery is higher than that of a new battery, it means that the capacity has decreased and actual testing is required; Method 2: The internal resistance of the same group of batteries should be basically the same because the use environment is exactly the same; when the internal resistance of a specific battery is higher than the average internal resistance of the same group, it means that the capacity has decreased; if the internal resistance is 30% higher than the average internal resistance, it should be paid close attention to, and if it is higher than 100%, it is considered that it needs to be replaced; Method 3: Compare the relationship between the internal resistance of the battery and the decrease in the actual remaining capacity of the battery. When the actual remaining capacity of the battery is between 100% and 70% of the nominal value, the corresponding relationship between the capacity decrease and the internal resistance increase does not change significantly. When the actual remaining capacity of the battery is less than 25% of the nominal value, the internal resistance increase trend gradually accelerates.

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